This application is filed under 35 U.S.C. 371 of International Application No. PCT/FR97/00715 filed Apr. 21, 1997.
The present invention relates to a cast wall with continuous reinforcement, to a method of making such a cast wall in the ground, and to shuttering for making such a cast wall.
Cast walls are structures made in the ground by digging a trench and filling the trench with a binder, generally concrete, which sets on site.
The trench can be dug under a slurry which is subsequently replaced by the binder.
To obtain good continuity of the cast wall, the binder must be cast on a single occasion over the full depth of the trench.
To this end, the cast wall is made in the form of successive contiguous panels.
Each panel is obtained by casting the binder into a length of trench that has been dug in line with a solidified panel that has already been made.
The panels are connected together in pairs by their side edges being mutually engaged with a shape that is defined by the shuttering, the engagement also being referred to as an end joint, extending transversely to the trench over the full depth thereof and being put into place prior to casting the binder.
In general, a cast wall is reinforced by reinforcement that is put into place in each length of the trench prior to casting the binder.
Nevertheless, in such a cast wall, the reinforcement is missing at the connections between panels, and as a result such connections constitute zones of weakness in the cast wall, such that the transmission of forces, in particular transverse bending, but also longitudinal compression and traction, does not take place properly from one panel to another, which can give rise to problems in the event of the ground moving, particularly in areas of high seismic activity.
Patent Document FR-A-2 517 717 describes a solution to that problem. It consists in fixing vertical elements of sheet piling to the ends of the panel reinforcement, which elements arc provided with locks that co-operate with one another to provide continuity of the reinforcement from one panel to another.
Nevertheless, that solution does not provide adequate transmission of forces applied to the reinforcement under the effect of external stresses.
In addition, engaging the locks in one another can become difficult when the reinforcing members are not properly aligned.
Finally, the means which are provided for protecting the locks while the casting material is being cast into the trenches are not really satisfactory.
A first object of the invention is to provide a cast wall constituted by a plurality of juxtaposed panels making it possible in particular to obtain a good distribution of the forces applied to the reinforcing members of the various panels, and which is implemented in improved manner.
To this end, the invention provides a cast wall constituted by a succession of panels touching via their end edges and made by casting a binder into contiguous lengths of trench dug in the ground in line with one another, each panel having reinforcement, said wall further including link means between the reinforcement of two contiguous panels, the wall being characterized in that the link means are separate from said reinforcement and comprise an anchor clement having a first end fitted with at least one vertical first locking clement and a second end engaged in one of said panels, and a link clement having a first end fitted with at least one second locking element suitable for co-operating with the first locking clement, and a second end engaged in the other of said panels.
Another object of the invention is to provide a method of making a cast wall, in particular of the above-defined type, and which does not have the drawbacks of the prior art.
To achieve this object, the invention provides a method of making a cast wall in the ground, in particular a wall as defined above, in which method a first length of trench is prepared in which end shuttering is placed and a binder is cast to obtain a first wall panel, and then, at the shuttering end, a second length of trench is prepared contiguous to the first and in line therewith, the shuttering is removed, and a binder is cast into the second length of trench to obtain a second wall panel adjacent to the first, which method is characterized by the fact that, prior to casting the binder in the first length of trench, reinforcement is placed therein together with a link element including locking ends that are positioned in the immediate vicinity of the shuttering, and during casting, said locking ends are prevented from being embedded in the binder so that they project from the first wall panel into the second length of trench after the shuttering has been removed, and prior to casting the binder in the second length of trench, reinforcement is put into place therein together with an anchor element which is secured to the locking ends of the link element, and in that the shuttering is secured to the link element prior to being put into place in the length of trench, the link and anchor elements not being directly secured to the reinforcement, but being engaged therein.
A third object of the invention is to provide shuttering for making a cast wall in a trench, in particular a wall of the type defined above, which shuttering does not have the drawbacks of the prior art.
To achieve this object, the invention provides shuttering for making a cast wall of the above-defined type, which shuttering is designed to be put into place against an end wall of a length of trench dug in the ground to obtain a wall panel by casting a binder into said length of trench, said shuttering including a face for bearing against the end wall of the length of trench, and opposite said bearing face, a casting face looking into the length of trench, the shuttering being characterized by the fact that it includes on its casting face, at least one recess suitable for receiving the locking element of a link element placed in the length of trench, each recess being closed by a vertical wall element provided with a vertical slot suitable for passing a sheet piling element fitted with the locking element and providing sealing between said sheet piling element and the wall of said recess.